Purifying petroleum oils



--'-tion, the greater the cost of treatment.

1 ably different with The result is that the Patented Apr. 19, 1932 UNITED STATES PATENT OFFICE BENJAMIN I1. SOUTHER, 0F PITTSBURGH, AND JOHN W. GREENE, OF WILKINSBURG,

PENNSYLVANIA, ASSIGNORS SYLVANIA, A CORPORATION OF TEXAS T0 GULF REFINING COMPANY, OF PITTSBURGH; PENN- PURIFYING PETROLEUM OILS No Drawing.

This invention relates to purifying petroleum products; and it comprises a method of acid treating petroleum oils and petroleum products wherein certain acid alkyl sulfates are used in lieu of, or in addition to, sulfuric acid, said acid alkyl sulfates being advantageously materials made by absorbing ethylene and other gaseous olefins from still gases with sulfuric acid; all as more fully hereinafter set forth and as claimed.

All petroleum oils and products, such as parafiin, are treated at one stage of manufacture or another with sulfuric acid. Sometimes fuming acid isused and sometimes weaker acid. Thesulfuric acid treatment is followed by a washing treatment with alkali. The exact nature of the actions exerted by the sulfuric acid in this treatment are still a. controversial matter and are probdifferent oils. The acid however decolorizcs the oil, removes sulfur and withdraws some components of the oil; these being the most reactive portions and hence the portions most subject to change. oil is stabilized against the action of air, light, etc. To some extent, the action of the acid causes polymerization. Some acid products in the nature of sulfonic acids go into the oil, whence they are withdrawn by the subsequent alkali treatment. All in all, the action of the acid is beneficial but it is accompanied with some loss of oil; and the greater the amount of acid used for a given degree of decoloriza- Sometimes, as in the case of cracked products containing considerable proportions of unsaturated compounds, the action of the sulfuric acid causes too great a loss of oil to permit thorough treatment.

We have found that certain alkyl sulfuric acids, carrying methyl, ethyl or propyl groups, exercise a specificand advantageous action in decolorizing oils; and we have fur ther found that this action can be usefully employed in connection with the ordinary sulfuric acid treatment. Alkyl sulfates suitable for our purposes may be obtained by causing ordinary still gases containing gaseous olefins to react with sulfuric acid; either Application filed April 7, 1928. Serial No. 268,369.

with the ordinary concentrated acid or with fuming acid. Still gases coming from stills 1 in which cracking is going forward contain ethylene and propylene as well as smaller quantities of higher olefins, such as propylene and butylene. Sulfuric acid of 1.84 speclfic gravity reacts readily with propylene (and butylene) but not with ethylene; and 1f there is any object in so doing, there may be a two-stage acid treatment of the still gas with acid; first with 1.84 acid which will form propyl sulfuric acid and then with fuming acid which will form ethyl sulfuric acid. But we ordinarily use a single treatment with fuming acid forming amixture of ethyl sulfuric and propyl sulfuric acids as the mixture is adapted to our purposes. Butyl sulfuric acid while not as desirable for our purposes as the other two, may still be used. However the amount of butylene in still gases going through condensers in contact with cool oily distillate is commonly quite small and its presence and the formation of butyl sulfuric acid may be disregarded. Still higher olefins, such as the amylenes, are substantially completely removed by the scrubbing action occurring 1n the condensers. In gases If the gas is not scrubbed, it may carry considerable proportions ofthe higher olefins.

In producing alkyl sulfuric acids from still gases, the gas and acid may be brought into reaction in any ordinary type of scrubbing apparatus. In general it is not worth while seeking any high degree of conversion of the acid into alkyl compounds since we ordinarily use an excess of sulfuric acid in our treating process.

Ethyl sulfuric acid can also the reaction of ordinary ethyl alcohol with sulfuric acid. Methyl sulfuric acid can be made by the reaction of methyl alcohol (methanol) with sulfuric acid.

In using still gases and sulfuric acid to form alkyl sulfates with an incomplete conversion of the sulfuric acid, as is done in the most advantageous embodiment of our inbe made by Q treatedwith 8, poundsofa mixture consisting Both have been found efficient for our puroses. Dialkylsulfates containing two alky-ls, such as methyl ethyl sulfate-,, may beused. But where we use the alkyl sulfate in conjunction with sulfuric acid as we on dinarily do, the use of the di-alkyl sulfates is equivalent to the use of the mono-alkyl sulfates.

On adding a small proportion of, any alkyl sulfate to petroleum oil and agitating, two layers are formed; The lower layer consists of the reagent carrying with it most. of the color-bearing constituents of. the oil',. while the upper layer is oil. This oil may: cmry a little of the alkyl' sulfuric acid in solution; the amount being the greater the higher the alkyl. This is one of the reasons for preferring methyl, ethyl and. propyl sulfuric acids to their higher homologs. Methyl sulfate and ethyl sulfate do not dissolve to any substantial extent. In the event, that any substantial amount of alkyl sulfuric acid remainswiththe, oil, the oil, may be steamed to cause hydrolysis. The upper layer of oil can finally be washed with soda as. usual.

Di-methyl sulfate and i but little soluble in petroleum oils, and the sol'ubi'lities of the mono-methyl sulfate and mono-ethyl sulfates are still less. On the other handythe di-butyl and, di-propyl sulfates are considerably more soluble,

a typical. embodiment of our invention,

a sample, of colored oil was, treated with a mixture of 90 per cent. dil-ethyl. sulfate and 10 per cent ofconcentrated', sulfuric acid, 10 per cent of the volume ofjthe oil-being used.

The oil was better decelorized than by the action of an equivalent amount of sulfuric acid. The color given was approxlmately No. 2 on the N. P. A. scale. Still better results were obtained with a mixture consistingof 80per. cent sulfuric acid and QO-per cent of ethyl hydrogen sulfate (ethyl sulfuric furic acid al'one.

acid).

Alkyl sulfuric acids, alone or in admixture with sulfuric acid, will; produce lighter colored oils than will the same amount of sul Good results are also obtained by treating the oil' first with allryl sulfuric acid, alone or in admixture with sulfuric acid, and; then following with a treat-- mentwith a sulfuric acid alone. The oilobtained'by this double treatment is unusually light in color andthelossof oil. is not, great.

A Venezuela; lubricating distillate treated? with.10. poundsof sulfuric; acid per barrel, gave. a darker productthan the same oil direthyl sulfate aredecole-rization and purification the process which comprises subjecting such an oil to the action of allryl hydrogen sulfates the said alkyl hydrogen sulfates being selected from the lower members of the alkyl series.

2. In the treatment of petroleum oil for de colori'zation and purification, the process which comprises subjecting such an oil to. the action of alkyl hydrogen sulfates in admirture with sulfuric acid; the said alkyl hydrogen sulfates being selected from the lower members of the alkyl series.

3. In the treatment of petroleum, oils for decolorization and purification the process which comprises subjecting such an oil tothc action of alkyl sulfates and subsequently treating with sulfuric acid; the said alkyl hydrogen sulfates being selected from the lower members of the alkyl. series.

In the purification of petroleum oils,.thc process which comprises treating such. an oil with; concentrated sulfuric acid contain.- ing alkyl sulfuric acids corresponding to the gaseous olefins ofstill gas resulting; from the cracking of hydrocarbon. oils.

5. In the purification of petroleum oils, the process which comprises subjecting said oils produced during a cracking step'to the action of mixed alkyl hydrogen sulfates resulting from the reaction of still gases and sulfuric acid, the said still gasesv being produced during said cracking step.

In testimony whereof,.we have hereunto affixed our signatures at Pittsburgh, Pennsylvania, this 5th day of April, 1928..

BENJAMIN L. SOUTHER- JOHN GREENE.. 

